1. Field of the Invention
This invention relates to a test tool for testing the sealing integrity of a well bore packer which can be used to retrieve the packer in a single run in the event of an unsuccessful test.
2. Description of the Prior Art
Well packers are known for selectively sealing and/or anchoring a tubing string to a surrounding well conduit or liner. Packers are known which can be set in the sealing/anchoring configuration on a wireline, by manipulation of a tubing string from which the packer is suspended, or by application of hydraulic pressure by means of the tubing string, for example. The packer typically comprises a tubular mandrel having circumferential sealing and gripping elements mounted on the exterior thereof for gripping and sealing engagement with the well bore.
The gripping members are extendible radially into gripping engagement with the well bore in response to relative axial movement of wedging surfaces which cooperate with the gripping elements to engage the well bore. The resilient seal elements are similarly expanded radially into sealing engagement with the well bore in conjunction with axial compression of the sealing members. The sealing and anchoring mechanisms are set in engagement with the surrounding well bore, in response to relative longitudinal movements of various packer components, affected either hydraulically or mechanically.
Once the packer has been set in the well bore, it is desirable to conduct a test of the sealing integrity of the packer to insure that the well annulus above the packer is sealed off from the well annulus below the packer. This can be done, for instance, by sealing the well head and applying pressure to the well annulus above the set packer. An appropriate pressure build- up can be detected at the well head which indicates that the well annulus above the packer is, in fact, sealed off from the well annulus below the packer.
Retrieving tools are also known for well packers which are used to retrieve a packer which has been released from the set condition to the well surface. In the prior art devices, testing and subsequent retrieval of a packer which did not test successfully required more than one run of the appropriate tool to the packer location within the well bore. That is, one run was typically required in conducting the packer test, and another run was required for a retrieval tool to engage and retrieve the unsuccessfully set packer.
The present invention has as its object the provision of a packer test tool which allows a packer to be tested, and in the same run, retrieved to the well surface in the event of an unsuccessful test. In the event of a successful test, the test tool is releasable from the set packer and can be retrieved to the well surface without the necessity of a wireline run.